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16 | |
16 | |
17 | cede; |
17 | cede; |
18 | |
18 | |
19 | DESCRIPTION |
19 | DESCRIPTION |
20 | This module collection manages coroutines. Coroutines are similar to |
20 | This module collection manages coroutines. Coroutines are similar to |
21 | threads but don't run in parallel. |
21 | threads but don't run in parallel at the same time even on SMP machines. |
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22 | The specific flavor of coroutine use din this module also guarentees you |
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23 | that it will not switch between coroutines unless necessary, at |
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24 | easily-identified points in your program, so locking and parallel access |
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25 | are rarely an issue, making coroutine programming much safer than |
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26 | threads programming. |
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27 | |
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28 | (Perl, however, does not natively support real threads but instead does |
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29 | a very slow and memory-intensive emulation of processes using threads. |
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30 | This is a performance win on Windows machines, and a loss everywhere |
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31 | else). |
22 | |
32 | |
23 | In this module, coroutines are defined as "callchain + lexical variables |
33 | In this module, coroutines are defined as "callchain + lexical variables |
24 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
34 | + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own |
25 | callchain, it's own set of lexicals and it's own set of perl's most |
35 | callchain, its own set of lexicals and its own set of perls most |
26 | important global variables. |
36 | important global variables. |
27 | |
37 | |
28 | $main |
38 | $main |
29 | This coroutine represents the main program. |
39 | This coroutine represents the main program. |
30 | |
40 | |
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56 | async { ... } [@args...] |
66 | async { ... } [@args...] |
57 | Create a new asynchronous coroutine and return it's coroutine object |
67 | Create a new asynchronous coroutine and return it's coroutine object |
58 | (usually unused). When the sub returns the new coroutine is |
68 | (usually unused). When the sub returns the new coroutine is |
59 | automatically terminated. |
69 | automatically terminated. |
60 | |
70 | |
61 | Calling "exit" in a coroutine will not work correctly, so do not do |
71 | Calling "exit" in a coroutine will do the same as calling exit |
62 | that. |
72 | outside the coroutine. Likewise, when the coroutine dies, the |
63 | |
73 | program will exit, just as it would in the main program. |
64 | When the coroutine dies, the program will exit, just as in the main |
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65 | program. |
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66 | |
74 | |
67 | # create a new coroutine that just prints its arguments |
75 | # create a new coroutine that just prints its arguments |
68 | async { |
76 | async { |
69 | print "@_\n"; |
77 | print "@_\n"; |
70 | } 1,2,3,4; |
78 | } 1,2,3,4; |
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79 | |
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80 | async_pool { ... } [@args...] |
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81 | Similar to "async", but uses a coroutine pool, so you should not |
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82 | call terminate or join (although you are allowed to), and you get a |
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83 | coroutine that might have executed other code already (which can be |
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84 | good or bad :). |
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85 | |
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86 | Also, the block is executed in an "eval" context and a warning will |
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87 | be issued in case of an exception instead of terminating the |
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88 | program, as "async" does. As the coroutine is being reused, stuff |
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89 | like "on_destroy" will not work in the expected way, unless you call |
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90 | terminate or cancel, which somehow defeats the purpose of pooling. |
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91 | |
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92 | The priority will be reset to 0 after each job, otherwise the |
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93 | coroutine will be re-used "as-is". |
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94 | |
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95 | The pool size is limited to 8 idle coroutines (this can be adjusted |
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96 | by changing $Coro::POOL_SIZE), and there can be as many non-idle |
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97 | coros as required. |
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98 | |
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99 | If you are concerned about pooled coroutines growing a lot because a |
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100 | single "async_pool" used a lot of stackspace you can e.g. |
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101 | "async_pool { terminate }" once per second or so to slowly replenish |
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102 | the pool. |
71 | |
103 | |
72 | schedule |
104 | schedule |
73 | Calls the scheduler. Please note that the current coroutine will not |
105 | Calls the scheduler. Please note that the current coroutine will not |
74 | be put into the ready queue, so calling this function usually means |
106 | be put into the ready queue, so calling this function usually means |
75 | you will never be called again unless something else (e.g. an event |
107 | you will never be called again unless something else (e.g. an event |
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98 | "Cede" to other coroutines. This function puts the current coroutine |
130 | "Cede" to other coroutines. This function puts the current coroutine |
99 | into the ready queue and calls "schedule", which has the effect of |
131 | into the ready queue and calls "schedule", which has the effect of |
100 | giving up the current "timeslice" to other coroutines of the same or |
132 | giving up the current "timeslice" to other coroutines of the same or |
101 | higher priority. |
133 | higher priority. |
102 | |
134 | |
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135 | Returns true if at least one coroutine switch has happened. |
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136 | |
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137 | Coro::cede_notself |
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138 | Works like cede, but is not exported by default and will cede to any |
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139 | coroutine, regardless of priority, once. |
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140 | |
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141 | Returns true if at least one coroutine switch has happened. |
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142 | |
103 | terminate [arg...] |
143 | terminate [arg...] |
104 | Terminates the current coroutine with the given status values (see |
144 | Terminates the current coroutine with the given status values (see |
105 | cancel). |
145 | cancel). |
106 | |
146 | |
107 | # dynamic methods |
147 | # dynamic methods |
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113 | Create a new coroutine and return it. When the sub returns the |
153 | Create a new coroutine and return it. When the sub returns the |
114 | coroutine automatically terminates as if "terminate" with the |
154 | coroutine automatically terminates as if "terminate" with the |
115 | returned values were called. To make the coroutine run you must |
155 | returned values were called. To make the coroutine run you must |
116 | first put it into the ready queue by calling the ready method. |
156 | first put it into the ready queue by calling the ready method. |
117 | |
157 | |
118 | Calling "exit" in a coroutine will not work correctly, so do not do |
158 | See "async" for additional discussion. |
119 | that. |
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120 | |
159 | |
121 | $success = $coroutine->ready |
160 | $success = $coroutine->ready |
122 | Put the given coroutine into the ready queue (according to it's |
161 | Put the given coroutine into the ready queue (according to it's |
123 | priority) and return true. If the coroutine is already in the ready |
162 | priority) and return true. If the coroutine is already in the ready |
124 | queue, do nothing and return false. |
163 | queue, do nothing and return false. |
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126 | $is_ready = $coroutine->is_ready |
165 | $is_ready = $coroutine->is_ready |
127 | Return wether the coroutine is currently the ready queue or not, |
166 | Return wether the coroutine is currently the ready queue or not, |
128 | |
167 | |
129 | $coroutine->cancel (arg...) |
168 | $coroutine->cancel (arg...) |
130 | Terminates the given coroutine and makes it return the given |
169 | Terminates the given coroutine and makes it return the given |
131 | arguments as status (default: the empty list). |
170 | arguments as status (default: the empty list). Never returns if the |
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171 | coroutine is the current coroutine. |
132 | |
172 | |
133 | $coroutine->join |
173 | $coroutine->join |
134 | Wait until the coroutine terminates and return any values given to |
174 | Wait until the coroutine terminates and return any values given to |
135 | the "terminate" or "cancel" functions. "join" can be called multiple |
175 | the "terminate" or "cancel" functions. "join" can be called multiple |
136 | times from multiple coroutine. |
176 | times from multiple coroutine. |
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177 | |
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178 | $coroutine->on_destroy (\&cb) |
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179 | Registers a callback that is called when this coroutine gets |
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180 | destroyed, but before it is joined. The callback gets passed the |
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181 | terminate arguments, if any. |
137 | |
182 | |
138 | $oldprio = $coroutine->prio ($newprio) |
183 | $oldprio = $coroutine->prio ($newprio) |
139 | Sets (or gets, if the argument is missing) the priority of the |
184 | Sets (or gets, if the argument is missing) the priority of the |
140 | coroutine. Higher priority coroutines get run before lower priority |
185 | coroutine. Higher priority coroutines get run before lower priority |
141 | coroutines. Priorities are small signed integers (currently -4 .. |
186 | coroutines. Priorities are small signed integers (currently -4 .. |
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164 | $olddesc = $coroutine->desc ($newdesc) |
209 | $olddesc = $coroutine->desc ($newdesc) |
165 | Sets (or gets in case the argument is missing) the description for |
210 | Sets (or gets in case the argument is missing) the description for |
166 | this coroutine. This is just a free-form string you can associate |
211 | this coroutine. This is just a free-form string you can associate |
167 | with a coroutine. |
212 | with a coroutine. |
168 | |
213 | |
169 | UTILITY FUNCTIONS |
214 | GLOBAL FUNCTIONS |
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215 | Coro::nready |
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216 | Returns the number of coroutines that are currently in the ready |
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217 | state, i.e. that can be swicthed to. The value 0 means that the only |
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218 | runnable coroutine is the currently running one, so "cede" would |
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219 | have no effect, and "schedule" would cause a deadlock unless there |
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220 | is an idle handler that wakes up some coroutines. |
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221 | |
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222 | my $guard = Coro::guard { ... } |
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223 | This creates and returns a guard object. Nothing happens until the |
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224 | object gets destroyed, in which case the codeblock given as argument |
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225 | will be executed. This is useful to free locks or other resources in |
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226 | case of a runtime error or when the coroutine gets canceled, as in |
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227 | both cases the guard block will be executed. The guard object |
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228 | supports only one method, "->cancel", which will keep the codeblock |
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229 | from being executed. |
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230 | |
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231 | Example: set some flag and clear it again when the coroutine gets |
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232 | canceled or the function returns: |
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233 | |
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234 | sub do_something { |
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235 | my $guard = Coro::guard { $busy = 0 }; |
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236 | $busy = 1; |
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237 | |
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238 | # do something that requires $busy to be true |
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239 | } |
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240 | |
170 | unblock_sub { ... } |
241 | unblock_sub { ... } |
171 | This utility function takes a BLOCK or code reference and "unblocks" |
242 | This utility function takes a BLOCK or code reference and "unblocks" |
172 | it, returning the new coderef. This means that the new coderef will |
243 | it, returning the new coderef. This means that the new coderef will |
173 | return immediately without blocking, returning nothing, while the |
244 | return immediately without blocking, returning nothing, while the |
174 | original code ref will be called (with parameters) from within its |
245 | original code ref will be called (with parameters) from within its |